The study of infant soothing may prove to be key to understanding infant regulation. Infant regulation involves a hierarchical map of physiological processes that organize the infant's behavior and supports optimal growth and development. To avoid pain, infants use their mothers in specific ways to calm and conserve energy. Little is known about the properties of maternal soothing and how they influence energy conservation. The candidate, an Instructor in Pediatrics at the University of Chicago, Section of Behavioral and Developmental Pediatrics, is experienced in the clinical assessment of infants' behavior and development and proposes additional research training in understanding the components of maternal soothing that engage natural antinociception mechanisms and their physiologic effects on the infant. The candidate's Specific Aims are: 1) Do normal term infants have a reduction of metabolic rate and other indices of pain when tasting various flavors- i.e., sucrose, formula milk, and colostrum-during and not during crying; 2) Are vulnerable infants (i.e., those small for gestational age (SGA) or those exposed to methadone) at risk for patterns of higher energy expenditure and decreased behavioral and physiologic responses to the natural nursing suckling treatments? This training program will include direction by interdisciplinary researchers as well as courses in neurobiology, physiology, statistics, and complex system data modeling. A series of experiments will identify the infant's behavioral, physiologic, and metabolic responses to various means of natural maternal soothing. By completing the proposed development and training program, the candidate will attain a comprehensive knowledge base of the assessment of infant metabolism and physiology and will pursue an independent program of research to apply this knowledge to populations of vulnerable and at-risk infants. Ultimately, the candidate will test the hypothesis that natural means of infant soothing conserve energy and protect infants from stress during the most critical times of somatic and brain development.